1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus to which developing cartridges are detachably mountable. Further, the present invention relates to an electrophotographic image forming apparatus to which process cartridges are detachably mountable.
Here, the electrophotographic image forming apparatus forms an image on a recording medium by using an electrophotographic image forming process. Then, examples of the electrophotographic image forming apparatus include, for example, an electrophotographic copying machine, an electrophotographic printer (for example, such as a color laser beam printer and a color LED printer), a facsimile machine, and a word processor.
In the process cartridge, at least one of a charging means, a developing means, and a cleaning means each serving as process means and an electrophotographic photosensitive member are integrated into a cartridge, which is detachably mountable to an apparatus main body. Note that the charging means, the developing means, and the cleaning means which act on the electrophotographic photosensitive member (hereinafter, referred to as a photosensitive member) are referred to as the process means. Note that, the process cartridge, which integrally includes the photosensitive member and the developing means, is referred to as a so-called integral type. Further, the process cartridge, which integrally includes the photosensitive member and the process means other than the developing means, is referred to as a so-called separation type.
The developing cartridge includes a developing roller, and contains a developer (toner) used to develop an electrostatic latent image (hereinafter, referred to as a latent image) formed on the photosensitive member by the developing roller. Note that, in a case of the developing cartridge, the photosensitive member is provided in the apparatus main body, or in the so-called separation type process cartridge (in this case, the process cartridge has no developing means).
Further, the developing cartridge and the process cartridge are detachably mounted onto an electrophotographic image forming apparatus main body (hereinafter, referred to as an apparatus main body), and contribute to an image forming process for forming an image on a recording medium.
Here, the developing cartridge and the process cartridge can be mounted to and detached from the apparatus main body by the user him/herself. For that reason, the maintenance of the apparatus main body can easily be performed by the user him/herself.
2. Description of the Related Art
In an electrophotographic image forming apparatus, for forming a color image, a method of superimposing developer images (hereinafter, referred to as “toner images”) formed with, for example, developers (hereinafter, referred to as “toner”) of a yellow color, a magenta color, a cyan color, and a black color is known. Further, a cartage system is widely adopted, in which a developer containing portion (hereinafter, referred to as a toner containing portion) containing toner and a developing member such as a developing roller are incorporated into a frame to obtain a unit (hereinafter, referred to as “developing cartridge”), whereby the toner and the developing roller can be replaced easily when they reach predetermined lives.
On the other hand, another cartridge system is also widely adopted, in which an electrophotographic photosensitive member and process means that acts thereon are integrated to obtain a unit (hereinafter, referred to as a process cartridge), and the photosensitive member and the process means can be replaced easily when they reach predetermined lives.
Further, a method of superimposing toner images includes a 4-pass system and a 1-pass system. According to the 4-pass system, developing devices are disposed side by side with respect to one photosensitive member, and latent images formed on the photosensitive member are successively developed by the respective developing devices to obtain toner images. Then, multiple toner images are superimposed on an intermediate transfer member to form a color image (see Japanese Patent Application Laid-Open No. 2001-117350). According to the 1-pass system, multiple photosensitive members are disposed side by side and latent images on the respective photosensitive members are developed to obtain toner images. Those toner images are successively transferred to a recording medium, whereby a color image is formed (see Japanese Patent Application Laid-Open No. 2006-189737). As one photosensitive member and one exposure unit can constitute the 4-pass system, the 4-pass system is desirable for the reduction in cost and the downsizing of an apparatus. On the other hand, according to the 1-pass system, though multiple photosensitive members and multiple exposure units are required, the printing speed of a color image can be enhanced.
In recent years, a color electrophotographic image forming apparatus (hereinafter, referred to as an image forming apparatus) is becoming widespread, and the needs of users are being diversified. Among them, cases where an image forming apparatus is used on a desktop are increasing, and hence there is a demand for the downsizing of the apparatus.
On the other hand, as illustrated in Japanese Patent Application Laid-Open No. 2001-117350, in an image forming apparatus, it is known that a developing cartridge is inserted in the apparatus main body with a developing roller being a leading edge. Further, as illustrated in Japanese Patent Application Laid-Open No. 2006-189737, in the image forming apparatus, it is known to insert a process cartridge into the apparatus main body with a photosensitive member being a leading edge.
As the apparatus main body is being downsized, the space for mounting a developing cartridge and a process cartridge is also decreasing. Therefore, there is a demand for a technology that enables a developing cartridge and a process cartridge to be replaced easily even in a narrow space. Particularly, in the case of a configuration in which a developing cartridge is inserted in the apparatus main body with a developing roller being a leading edge, the developing roller may come into contact with an adjacent developing cartridge mounted onto the apparatus main body. This contact may damage the developing roller.